Mazda 3 Sedan 2020 Owner's Manual page 524

If Trouble Arises
Battery Runs Out
Connect the negative cable to a good ground point away from the battery:
Connecting the end of the second jumper cable to the negative (–) terminal of the
discharged battery is dangerous.
A spark could cause the gas around the battery to explode and injure someone.
Route the jumper cables away from parts that will be moving:
Connecting a jumper cable near or to moving parts (cooling fans, belts) is
dangerous. The cable could get caught when the engine starts and cause serious
injury.
CAUTION
Use only a 12 V booster system. You can damage a 12 V starter, ignition system, and
other electrical parts beyond repair with a 24 V power supply (two 12 V batteries in
series or a 24 V motor generator set).
1. Move the booster vehicle so that its battery is as close as possible to your
vehicle's battery.
2. Make sure that the power such as for the headlights and air conditioner is turned
off.
3. Remove the battery cover.
4. Turn off the booster vehicle's engine and connect the jumper cables in the
following order.
Make sure that the jumper cables are securely connected so that they do not
disconnect due to engine vibrations.
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